To analysis the tumor initiating capability, NOD/SCID mice were transplanted with various amounts of CD133^-EpCAM^-, CD133⁺EpCAM^-, CD133^-EpCAM⁺ and CD133⁺EpCAM⁺ cells. In 10,000 cells group, CD133⁺EpCAM⁺ cells possessed higher tumorigenicity and faster tumor growth than other three phenotypes. In 5,000 and 1,000 cells groups, CD133⁺EpCAM⁺ cells possessed higher tumorigenicity and faster tumor growth compared to CD133^-EpCAM⁺ and CD133^-EpCAM^- cells. In 500 cells group, only CD133⁺EpCAM⁺ cells formed tumor mass (Table 1, Fig. 6A). For example, CD133⁺EpCAM⁺ cells, but not CD133^-EpCAM^- cells, could efficiently initiate tumors in NOD/SCID mice (Fig. 6B). Sorted CD133⁺EpCAM⁺ cells formed similar histological features of xenograft tumors as unsorted Huh7 cells (Fig. 6C). The results showed that CD133⁺EpCAM⁺ cells embodied the increased tumorigenicity in vivo.

 Table 1 

Tumorigenicity of various Huh7 phenotypes in NOD/SCID mice.